Three approaches:
https://prod.liveshare.vsengsaas.visualstudio.com/join?A72DCEC3593FC85B69CC96FE2D433E97E909
Partially abandoned, because I am not familiar with USB protocols. Also, the captured packets are hard to be interpreted.
Ongoing. Most promise one. Progress: 4/10
The source code is poorly written, so it takes time to find and verify bytecodes for each operation.
I am still determining whether GRBL should be tried. Because it is irreversible.